队列（Queue）是一种先进先出（FIFO）的线性数据结构，插入操作在队尾（rear）进行，删除操作在队首（front）进行。

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队列ADT（抽象数据类型）一般提供以下接口：

① Queue() 创建队列
② enqueue(item) 向队尾插入项
③ dequeue() 返回队首的项，并从队列中删除该项
④ empty() 判断队列是否为空
⑤ size() 返回队列中项的个数

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#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Created by xuehz on 2017/8/8

class Queue():
    def __init__(self,size):
        self.queue = []
        self.size = size
        self.head = -1
        self.tail = -1

    def Empty(self):
        if self.head == self.tail:
            return True
        else:
            return False

    def Full(self):
        if self.tail - self.head +1 == self.size:
            return True
        else:
            return False

    def enQueue(self, content):
        if self.Full():
            print 'Queue is Full'
        else:
            self.queue.append(content)
            self.tail = self.tail+1

    def outQueue(self):
        if self.Empty():
            print 'Queue is Empty'
        else:
            self.head = self.head+1
     
 

class Queue:
  def __init__(self):
    self.items = []
  def enqueue(self, item):
    self.items.append(item)
  def dequeue(self):
    return self.items.pop(0)
  def empty(self):
    return self.size() == 0
  def size(self):
    return len(self.items)